Consider the following table definition, where the primary keys are underlined. Give an expression in relational algebra for each of the following queries. Athlete (aID integer, aName string, ranking integer, age integer) Event (eID_string, eName string, eLocation string) Competes (aID integer, eID string, sport string, year integer) 1. Find the names of athletes who have competed in event 1Sk8P (eiD '1Sk8P) 2. Find the names of athletes who have competed in the event Dew Tour (eName 'Dew Tour) 3. Find the names of the events an athlete named Dennis competed in (aName - 'Dennis') 4. Find the names of the athletes who have competed in at least one Event 5. Find the names of athletes who have competed in 'XGames' or 'Dew Tour 6. Find the names of athletes who have competed in both 'XGames' and 'Dew Tour 7. Find the alD of athletes over the age of 19 who have not competed in xGames